[Centos] Up2date Unknown GPG signatures

I just ran up2date on new Centos-3.1 installation and
received about 5 of these errors.  Is this something
to be concerned about? 

The package kernel-2.4.21-15.0.4.EL is signed with an
unknown GPG signature. Continue
The package kernel-utils-2.4-8.37.3 is signed with an
unknown GPG signature. Continue?
The package GConf2-2.2.1-4 is signed with an unknown
GPG signature. Continue?

It is using the default sources file from the CD. 
http://mirror.centos.org/




		
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